- HLA matched donor Sibling donors must be a confirmed match at HLA-A, B, and DRB1 Other related and non-related donors must be matched at HLA-A, B, C, DRB1, and DQB1 A donor homozygous for one allele only at HLA-A, B, C, DRB1, or DQB1 allowed (1 antigen mismatch for graft-versus-host disease, 0 antigen mismatch for graft-rejection)